What is the difference between quattro ultra and permanent Quattro in Audi cars?

I am looking to buy an Audi car and I am confused about the difference between the quattro ultra and permanent Quattro systems. Can someone explain it to me?

The main difference between the two systems is that quattro ultra is a more advanced and efficient version of the permanent Quattro system. While permanent Quattro constantly sends power to all four wheels, quattro ultra only sends power to the front wheels when necessary, saving fuel and improving handling.

Quattro ultra is a relatively new technology developed by Audi, while permanent Quattro has been used in their cars for decades. Quattro ultra uses sensors to determine when all-wheel drive is necessary, while permanent Quattro relies on a 40/60 power split between the front and rear wheels.